The Methodology and Statistics Core performs several important tasks essential for satisfying the goals of the Center. These include (1) conducting psychometric analyses on all instruments used in CEDAR to ensure their appropriateness for use in the research, (2) conduct analyses of new constructs proposed by Center faculty, (3) providing statistical consultation, (4) conducting statistical analyses, and (5) conducting methodological research on various topics in statistics In addition, this Core will continue research on development of a multi-dimensional inventory to measure ATOD tomography spanning adolescence to adulthood as well as evaluate the potential utility of measuring ATOD topography employing a computerized adaptive test (CAT) format. The ATOD topography inventory provides a uniform schema for use by all CEDAR investigators. It also affords the opportunity, when subsequently standardized in a population based study, to map ATOD topography in a more comprehensive fashion that is currently possible. The CAT version, potentially adaptable to a palmtop computer, may thus expedite comprehensive assessment in a user-friendly format for adolescents without laborious scoring and personnel costs while requiring substantially reduced assessment time. In summary, this Core has both service functions central to the Center's research mission and investigative objectives which have direct practical application.